This is a first revision of a competing renewal to continue research on the use of voucher-based incentives to promote cigarette smoking cessation and relapse prevention among pregnant and recently postpartum women. Maternal cigarette smoking is the leading preventable cause of poor pregnancy outcomes and pediatric morbidity and mortality in the U.S. Efficacious interventions have been developed for smoking cessation during pregnancy, but cessation rates are low, typically under 20%. Efficacious interventions to prevent postpartum relapse remain to be developed. This application seeks support for a Stage II behavioral therapies development project to continue examining interventions to increase smoking cessation above the low levels noted above and to decrease postpartum relapse. With regard to cessation, we conducted studies during the prior funding period showing that voucher-based incentives delivered contingent on biochemically-verified abstinence promote smoking cessation in approximately 40% of women who were still smoking at their 1st prenatal visit compared to only 9% in a control condition. Comparable studies on decreasing postpartum relapse among women who were smokers upon learning of their pregnancy but quit by their 1 prenatal visit (spontaneous quitters) supported the efficacy of abstinence-contingent vouchers for preventing antepartum but not postpartum relapse. We also completed secondary studies on appropriate cutpoints for biochemically verifying smoking status in pregnant women, characterizing the quantitative relationship between smoking exposure and fetal growth, the time-course of depressive symptoms during pregnancy in smokers and abstainers, and the incidence and severity of nicotine withdrawal. While the treatment effect on smoking cessation during pregnancy noted above is at least two-fold greater than usual outcomes, the majority of women, especially heavier smokers (= or >10 cigs/day), failed to quit. In Study 1 of this application we propose to experimentally examine whether a revised voucher program designed to increase initial abstinence and encourage additional quit attempts among those who initially fail can promote cessation at the end-of-pregnancy assessment in the majority of women treated (= or >60%). Considering that nobody has succeeded in decreasing postpartum relapse among spontaneous quitters, we are not surprised that our first effort was unsuccessful. In Study 2 of this application we propose to experimentally test whether a revised voucher-based incentive program designed to more effectively reinforce sustained abstinence will decrease postpartum relapse. We are also proposing to continue secondary studies on biochemical verification of smoking status, fetal growth, and predictors of postpartum relapse. Overall, the proposed studies have the potential to contribute important new information on effective treatments for one of our nation's most daunting drug abuse problems.